Manufacture of electrically insulating polysulphones

ABSTRACT

New polymeric materials containing sulphone groups in the polymer chain are particularly suitable for moulding to give strong transparent products of high softening point and may be used as electrical insulants in condensers.

This is a continuation, of application Ser. No. 735,563, now abandoned,filed June 10, 1968. The lastmentioned application is a divisionalapplication of application Ser. No. 657,538, filed Aug. 1, 1967, nowabandoned and is a continuation-in-part of application Ser. No. 320,508,filed Oct. 31, 1963.

The present invention relates to the manufacture of polysulphones andalso to new polymeric materials containing sulphone groups in thepolymer chain.

According to the present invention we provide a process formanufacturing polysulphones which comprises melting together at leastone first compound containing two aromatically bound sulphonyl halidegroups and at least one second compound which contains at least twoaromatically bound hydrogen atoms in the presence of from 0.05 to 5% byweight of the compounds of a salt of iron which is soluble in thepolymerisable mixture of antimony pentachloride.

According to a modification of the process, at least one single organiccompound containing a sulphonyl halide group and a hydrogen atom eachbound to an aromatic ring may replace the combination of theaforementioned first compound and second compound.

THE MONOMERS

The first compound will have two sulphonyl halide (--SO₂ X) groups eachattached to an aromatic nucleus. They may be attached to the same ordifferent nuclei. The nucleus may be derived from benzene or apolynuclear aromatic hydrocarbon. By a polynuclear aromatic hydrocarbonwe mean a hydrocarbon containing two or more condensed rings of which atleast one is aromatic. Examples are indene, naphthalene, anthracene,phenanthrene and chrysene.

However, we prefer not to use disulphonyl halides derived from compoundssuch as anthracene, phenanthrene or chrysene which contain three or morecondensed aromatic nuclei since their use may lead to cross-linking inthe polymeric products. Although this tendency may be reduced bydeactivating all but two of the rings by substituting the aromatichydrogen atoms by, for example, nitro, carboxylate, aldehyde, ketone,nitrile, sulphone, sulphate or sulphonate groups, we prefer to usepolynuclear aromatic hydrocarbons containing not more than two aromaticnuclei, such as naphthalene, indene and fluorene. We further prefer touse the disulphonyl halides in which each sulphonyl halide is attachedto a benzene or substituted benzene nucleus.

These compounds fall into three categories represented by the followingstructures: ##SPC1##

Or substituted derivatives thereof where one or more of the aromaticallybound hydrogen atoms are replaced by other monovalent atoms or groups.

In III, Y represents any suitable divalent bridging radical. Forinstance Y may be --O--, --S--, --SO--, --SO₂ --, --CO--, --CO.NH--,--CO.O--, --O.CO.O--, a divalent hydrocarbon radical, a divalent etheror thioether radical or a residue of a diol. By a residue of a diol wemean the divalent structure obtained by removing the two hydroxylhydrogen atoms from an organic compound containing two hydroxyl groups.

Our specified first compounds having the structure I are benzenedisulphonyl halides and any or all of the four remainingaromatically-bound hydrogen atoms of the benzene ring may be replaced byother substituents, if desired. Common examples are the 1,3- and 1,4-benzene disulphonyl halides. We prefer the 1,3 derivatives because oftheir ease of preparation. Possible substituents for the benzene ringinclude, for example, monovalent hydrocarbon, ether and thioether groupsand their halogen substituted derivatives, hydroxy groups, thiol groups,carboxylate groups, amine and substituted amine groups, nitro andnitroso groups, aldehyde groups, ketone groups, nitrile groups, sulphonegroups, sulphonate groups, sulphate groups, and halogen atoms. We preferthe substituents, if any, to be "meta" to the SO₂ X groups sincesubstitution in the ortho positions tends to cause steric hindrance tohe polymerisation.

Substitution on the benzene ring tends to affect the activity of thesulphonyl halide in polymerisation and both the nature of thesubstituent and the position of the substitution plays a part. Theeffect of such substitution may be discovered by simple experimentation.We have found in general that the presence of groups which are known toactivate electrophilic substitution in the meta position tends to havean adverse effect on our polymerisation and we prefer, therefore, not touse compounds having, for example, nitro, carboxylate, aldehyde, ketone,nitrile, sulphone, sulphate or sulphonate groups. Substituent groupscontaining active hydrogen atoms (for instance, amine, mono-substitutedamine, thiol and hydroxyl groups) tend to react with the polymerisationcatalysts and we prefer that they are absent also. Our preferredsubstituents are halogen atoms, hydrocarbon, ether and thioether groupsand halogen substituted derivatives of these groups. Examples of benzeneand substituted-benzene disulphonyl chlorides arebenzene-1,3-disulphonyl chloride; toluene-2,4-disulphonyl chloride;toluene-3,5-disulphonyl chloride; octyl benzene-3,5-disulphonylchloride; chlorobenzene-2,4-disulphonyl chloride andanisole-3,5-disulphonyl chloride and benzene-1,4-disulphonyl chloride.

We have found in general that where our specified first compound hasboth its sulphonyl halide groups attached to the same benzene ring, thepolymerisation process is undesirably slow and we prefer, therefore, touse those compounds having the structure II or III. Of those having thestructure II or III, we find it most convenient to use the4,4'-disulphonyl chloride derivatives because of their availability.Substituted derivatives of those compounds may also be used where eitherthe hydrogen atoms of the aromatic nuclei or the hydrogen atoms attachedto carbon atoms of the bridging group (if any) or both are substitutedby other monovalent atoms or groups. Where the substitution is on thearomatic nuclei, the same rules for activation apply as described forfurther substitution of compounds having the structure I. Thus, ourpreferred substituents are halogen atoms, hydrocarbon, ether andthioether groups and their halogenated derivatives.

In general, we prefer that there are no large substituents in thepositions ortho to the sulphonyl halide groups since such substituentstend to cause steric hindrance to he progress of the polymerisation. Wefurther prefer that in the aromatic nuclei only the hydrogen atoms orthoto the bridging group are substituted by other atoms or groups.

In compounds of the structure III we prefer that the bridging groups arenot those, such as sulphone or ketone groups, which would tend todeactivate the aromatic nuclei and therefore inhibit the polymerisationreaction, or groups (for instance sulphoxide, carbonate, carboxylate,carbamate, amido or divalent aliphatic hydrocarbon groups containingaliphatic carbon atoms in the chain between the aromatic nuclei oraliphatic diol residues) which may be unstable under the conditions ofthe reaction. Furthermore, where the bridging group contains an aromaticnucleus, we prefer that the said nucleus is deactivated so that itcannot take part in the polymerisation, so promoting cross-linking. Wealso prefer that the bridging groups are such that there are not morethan 4 atoms in the chain between adjacent aromatic nuclei because withlonger bridging groups the products obtained tend to have undesirablylowered softening points.

Our preferred bridging groups are oxygen atoms, sulphur atoms, andgroups having the structure ##SPC2##

where K and K' are selected from the group consisting of oxygen andsulphur atoms and L is --CO-- or --SO₂ --.

Our specified first compounds may contain a third sulphonyl halide groupwhere it is desired to obtain a cross-linked product.

The second compound in our two component process may be any aromaticcompound containing at least two aromatically bound hydrogen atoms. Thearomatic compound may be a polynuclear aromatic hydrocarbon such asindene, anthracene, phenanthrene or chrysene (but preferably onecontaining not more than two aromatic nuclei, such as naphthalene,indene or fluorene) or may be a compound having the structure I, II orIII as hereinbefore described but replacing the sulphonyl halide groupsby hydrogen atoms. Where the aromatic compound comprises a singlebenzene ring as in structure I it may have up to four substituents andwhere it has the structure II or III each benzene ring may contain up tofive substituents (including the bridging group) thus leaving in allcases at least two hydrogen atoms attached to aromatic nuclei.

Where substituted aromatic compounds are chosen, the preferred types andpositions of the substituents on the aromatic nuclei are as describedabove for the disulphonyl halide compounds.

In general, we have found that if benzene or a substituted benzene ischosen as the second compound in our two-component process, the reactionis very slow and therefore we prefer to use those compounds containingthe structures II or III, omitting the sulphonyl halide groups.

Thus, our preferred second compounds are those having the structure IIor III where Y is an oxygen atom, a sulphur atom or a group having thestructure ##SPC3##

as hereinbefore defined, or substituted derivatives of structures II andIII having halogen atoms, monovalent hydrocarbon, ether or thioethergroups or halogen substituted derivatives thereof, peferably halogenatoms, alkyl groups containing from 1 to 4 carbon atoms or alkoxy groupscontaining from 1 to 4 carbon atoms, on one or more of the positions inthe aromatic nuclei ortho to the bridging groups.

In general, where both the first and second compounds in thepolymerisation reaction have the structure II, the products tend to beinflexible and brittle and therefore we prefer that at least one of thecompounds has the structure III.

Accordingly in a preferred embodiment of our process for manufacturingpolysulphones by a two-component process, the first compound is selectedfrom those having the structure ##SPC4##

and the second compound is selected from those having the structure##SPC5## where Z and Z' are selected from the group consisting of directlinkages, oxygen atoms, sulphur atoms and groups having the structure##SPC6##

where K and K' are each selected from the group consisting of oxygen andsulphur atoms and L is --SO₂ -- or --CO--; and at least one of Z and Z'is not a direct linkage and R₁, R₂, R₃ and R₄ are each selected from thegroup consisting of hydrogen atoms, halogen atoms, alkyl groupscontaining from 1 to 4 carbon atoms and alkoxy groups containing from 1to 4 carbon atoms.

Examples of such compounds are diphenyl, diphenyl ether, diphenylsulphide, di-(-o-chlorophenyl) sulphide, di(2-methoxyphenyl) ether,2-phenoxytoluene, di-3,5-dichlorophenyl ether, di-o-tolyl ether, and4,4'-diphenoxydiphenylsulphone, and their 4,4'-disulphonyl chloridederivatives.

Mixtures of our specified first and second compounds may be polymerisedby the process of the invention to give mixed polymers if desired. Bycareful choice of the ingredients, considerable variation of thephysical properties of the polymeric products may be achieved. Ingeneral, it is preferred to use equimolar amounts of first and secondcomponents. However, where it is desired to limit the molecular weight,this may be done by adding an excess of one or other of the components.Alternatively such molecular weight control may be effected by adding tothe polymerisation a monofunctional compound. By a monofunctionalcompound we mean one which has only one active atom or group under theconditions of the reaction. An example is a 3,5-disubstituted benzenesulphonyl halide such as 3,5-dichlorobenzene sulphonyl chloride.

In a further embodiment of the invention the disulphonyl halide compoundor compounds used in the polymerisation may be replaced in part by oneor more compounds containing two carbonyl halide groups each of which isbound to an aromatic nucleus. Such compounds may have the structures I,II or III but with CO.X groups in place of the SO₂.X groups. Thepreferments for these carbonyl halide compounds are in general the sameas those for the disulphonyl halide compounds and the products obtainedfrom such a polymerisation are mixed polymers containing --CO-- and--SO₂ -- groups in the polymer chains. Products having a wide variety ofphysical properties may be obtained by varying the choice andconcentrations of the compounds taking part in the polymerisationreaction. However, those containing groups derived from dicarbonylhalides generally tend to be crystalline.

In our modified process wherein the combination of first and secondcompounds is replaced by a single compound as described hereinbefore,any aromatic compound containing both an aromatically bound sulphonylhalide group and an aromatically bound hydrogen atom, on the samenucleus or on different nuclei, may be used. Examples are themonosulphonyl halides of benzene and polynuclear aromatic hydrocarbons(preferably containing not more than two aromatic nuclei) and compoundshaving the structures II and III as hereinbefore described but excludingone of the sulphonyl halide groups. The rules for the preferred choiceof such compounds are the same as for the first and second compounds ofour two-component process, i.e., we particularly prefer those having thestructure ##SPC7##

where Z, R₁, R₂, R₃ and R₄ are as defined hereinbefore.

Mixtures of these mono-sulphonyl halide compounds, to give mixedpolymers, may be used if desired and where such mixtures are used, thismodified process is particularly suitable because of its flexibility.Aromatic mono-carbonyl halides of similar form may also be copolymerisedwith these sulphonyl halide compounds to give mixed polymers. Limitationof the molecular weight of the products of this modified process may beobtained, where desired, by the addition to the polymerisation mixtureof a monofunctional compound as hereinbefore defined.

It will be appreciated that an equimolar mixture of our specified firstand second compounds may also be reacted with one or more of ourspecified monosulphonyl halides to give high polymeric products by theprocess of our invention. Variation of the mixture of first and secondcompounds from equimolar proportions will tend to reduce the molecularweight.

THE PROCESS

The polymerisation may be effected by heating together the component orcomponents and the catalyst alone or in the presence of an inertsolvent. Suitable solvents are highly polar compounds such as cyclictetramethylene sulphone, nitromethane and nitrobenzene. However, thepresence of solvents generally slows down the reaction and also, sinceonly the low polymers tend to be soluble in the solvents, the productsare generally only of low molecular weight. Furthermore, use of asolvent is economically unattractive and therefore we generally preferto work in its absence.

In our two-component process, we prefer that the disulphonyl halidecompounds and the second components be added in approximately equimolarproportions. However the proportions may be varied from equimolarquantities where it is desired to restrict the molecular weight of theproducts. In the modified process, where two or more components are usedthey may be added in any desired proportions.

Suitably, the polymerisable component or components are heated untilmolten and thoroughly mixed before the catalyst is added to the melt. Aspolymerisation continues the temperature is raised in order to maintainthe ingredients in the molten state and when the maximum requiredtemperature is reached, this is maintained for a further period of time,generally of the order of 2 to 3 hours in order to allow completion ofthe polymerisation. During the polymerisation, hydrogen chloride isevolved and must be removed, e.g. by effecting the reaction undervacuum. The reaction is preferably conducted in the presence of an inertgas such as nitrogen in order to ensure the absence of oxygen above themelt. Where it is desired to obtain polymer of high molecular weightwithin a reasonable time period, temperatues of 200°C. or more aregenerally required.

The catalysts used in the polymerisation are iron salts which aresoluble in the polymerisable mixture or antimony pentachloride; thesalts may be those of ferrous or ferric iron. Because the molecularweights of the polymers formed by this process generally increase withincrease in the temperature at which polymerisation is effected, it ispreferred to use catalysts which do not dissociate to inert productseven at the higher temperatures of from 200° to 250°C. Antimonypentachloride tends to dissociate at about 170°C. and is thereforeineffective in producing high molecular weight products.

Examples of iron salts that may be used are ferric fluoride, ferricchloride, ferrous bromide, ferrous iodide, ferric orthophosphate andferrous and ferric acetoacetonates. In general, we prefer to use theiron halides because of their useful catalytic activity and ferricchloride is particularly preferred because of its ready solubility in awide variety of solvents, the ease with which it may be obtained in verypure form and because its use under suitable conditions consistentlygives polymers of high molecular weight.

The catalysts are used in amounts of from 0.05 to 5% by weight of thepolymerisable ingredients. Generally, amounts of less than 0.05% induceonly very slow polymerisation but it is preferred to use not more than1% by weight of catalyst because of the difficulty in removing thecatalyst residues from the polymer. Amounts of from 0.1 to 0.5% arepreferred.

As we have already stated, the high molecular weight polymers (which ingeneral are those having the better all-round physical properties) areobtained within a reasonable period of time by effecting thepolymerisation at high temperatures, generally of the order of 200°C. orabove. This is because increase of molecular weight is accompanied byincrease in softening point of the polymer and when the molecular weightof the polymer formed during the polymerisation becomes such that itssoftening point attains or surpasses the polymerisation temperature, thereaction mass will tend to solidify and polymerisation will then proceedonly very slowly, if at all. However, we have now found that there is anundesirable tendency for the polymers to cross-link if they aresubjected above certain temperatures, generally about 250°C. duringpolymerisation. On the other hand, only if the polymerisationtemperature is maintained at or above about 250°C. are products of goodphysical strength consistently obtained. The cross-linked polymers aregenerally insoluble in all common solvents and tend to be intractable.They are therefore of little value as moulding, solvent-spinning orsolvent-casting materials.

Therefore, as a further embodiment of our invention we provide animproved process for obtaining polymers of high molecular weight inwhich the polymerisable material is subjected in the presence of thecatalyst to a temperature above its melting point but below that atwhich substantial cross-linking of the polymeric product would occuruntil the mixture becomes viscid or solid; cooling it, comminuting thecooled mixture, and thereafter reheating the comminuted product to atemperature below that at which substantial cross-linking would occur inorder to complete the polymerisation.

In our preferred process the polymerisable material is charged into thepolymerisation vessel and heated until it is molten. Where two or morecompounds are used, they are thoroughly mixed together when molten. Thepolymerisation catalyst is then dissolved in the melt. In general, thereis a short induction period and then rapid evolution of hydrogen halide(generally hydrogen chloride gas) denotes the commencement ofpolymerisation.

Since some of the reagents in the polymerisation process may react withwater it is preferred, where products of high molecular weight arerequired, to rigorously exclude moisture from the reaction vessel duringthe polymerisation and, in our improved process, during the comminutionstep. It is also preferred to effect the reaction in the absence of air,for example by evacuating the reaction vessel or purging it with aninert gas such as nitrogen or both.

The course of the polymerisation may be followed by measuring theevolution of hydrogen halide.

After the addition of the catalyst, the molten mixture is maintained atan elevated temperature until it becomes a highly viscous mass orsolidifies. In general, we have found that the polymeric material tendsto cross-link if the polymerisation medium is subjected to temperaturesabove about 250°C. and therefore we prefer not to work above thistemperature. In order to ensure that no cross-linking occurs, we preferto operate the first stage of the polymerisation process at or below200°C. until the product becomes viscid or solid.

The rapid increase in viscosity and eventual solidification of the meltis caused by the polymers attaining a molecular weight which gives thema softening point above the temperature of the polymerisation mixture.The time before solidification occurs depends upon the temperature ofthe melt: increase in temperature generally resulting in a reduction inthe time required. Therefore we prefer to use as high a temperature aspossible without cross-linking occurring. Temperatures of from 150° to200°C. have been found generally suitable.

The melt generally forms a viscid or solid foamed mass in the reactionvessel and this mass is then cooled and ground to a fine powder. Thecomminution is effected under anhydrous conditions in order to avoiddestroying the catalyst. Any suitable grinding means may be used. Thefine powder is then reheated and maintained at an elevated temperaturebelow that at which cross-linking would occur until polymerisation iscomplete. It is preferred that this heating step is effected underreduced pressure in order to aid the removal of the hydrogen chloridegas. Temperatures of from 150° to 250°C. are very suitable. The timerequired for the second heating step also depends upon the temperatureof the heat treatment, higher temperatures requiring shorter times.Times of from 15 minutes to a few hours are normally very suitable,depending on the molecular weight required and the scale of thereaction. The end of the reaction is generally indicated by thecessation of evolution of hydrogen halide gas.

After the polymerisation, it is preferred to remove the catalystresidues from the product since their presence may cause discolourationand sometimes degradation. Any suitable process may be used. Forexample, the polymer may be ground down to powder and treated withhydrochloric acid in an alcohol, preferably methanol, under reflux.However, this process is frequently inadequate and removes only smallamounts of the catalyst. Therefore we prefer to use the processdescribed in our copending British application No. 38974/63 in which thepolymer is dissolved in a suitable solvent such as dimethyl formamide ornitrobenzene and treated in solution with a complexing agent, preferablya chelating agent, for the catalyst. The complex is then separated fromthe polymer. The treated polymer may be re-precipitated by pouring thefiltered solution into a suitable non-solvent for the polymer such as analcohol, preferably methanol, or acetone, and is then thoroughly dried,preferably at elevated temperature and preferably under vacuum.

The products often tend to suffer from "setting-up" during processingoperations which necessitate holding the polymers at elevatedtemperatures and particularly in molten form. It is believed that thissetting-up which may be recognised by an increase in the viscosity ofthe melt, is due to decomposition of terminal sulphonyl or carbonylhalide groups to yield active points in the polymer chain. These activepoints precipitate a cross-linking reaction which may ultimately reducethe polymer to an insoluble, infusible mass which is useless for normalfabrication processes in plastic art, such as injection moulding,compression moulding or extrusion. The process of setting-up may besubstantially reduced or eliminated entirely by the process described inour copending British application No. 38973/63, which comprises reactingthe polymers in solution and below the temperature at which setting-upwould occur with an organic compound having one or two groups permolecule which will react with the sulphonyl halide or carbonyl halidegroups in the polymer to yield products which are stable at temperaturesat which the polymer is molten. Suitable compounds are aromatic amines,particularly aniline, and the process may suitably be effected before,after or during the process for removing the catalysts from the polymer.In such cases, any excess of the compound may be removed from thepolymer at the same time as the catalyst complexes.

THE POLYMERS

The products of the process are polymers containing repeating unitswherein a sulphone group is tied to two aromatic residues. Theun-crosslinked products are thermoplastic materials, generally of highsoftening point, which may be used in any suitable process known forfabricating plastic material. Those of high molecular weight may betough solids which are substantially inert to a wide variety ofchemicals, both acid and alkaline. They may be melt-spun to give fibresand filaments or cast from solution in suitable solvents to give films.They may be admixed with other suitable ingredients such as pigments,heat and light stabilisers, plasticisers, lubricants, mould-releaseagents and fillers and may be blended with other polymeric materials ifdesired.

The process of the invention may be operated to produce a novel group ofpolysulphones which are of high softening point and of excellent thermalstability at high temperatures even above their softening points. Theamorphous polymers of this group are soluble in a number of organicsolvents, are strong, frequently transparent and are stable for longperiods in molten form. They are, therefore, eminently suitable forfabrication by suitable plastics shaping processes such as injection andcompression moulding and extrusion.

Thus, according to a further feature of our invention we provide newpolymeric materials formed of repeating units having the structure--Ar--SO₂ -- where Ar is a divalent aromatic residue derived frombenzene, a polynuclear hydrocarbon, diphenyl, a compound having thestructure ##SPC8##

where P is --O--, --S--, --SO--, a divalent hydrocarbon radical, asubstituted divalent hydrocarbon, a residue of a diol containing onlycarbon atoms or groups of the structure --C--O--C--, and --C--S--C--, inthe chain between the hydroxyl groups, or substituted derivatives of anysuch aromatic residues wherein one or more of the hydrogen atoms boundto aromatic rings are substituted by other monovalent atoms or groups,and Ar may vary from unit to unit in the polymer chain. Where theresidue is derived from a polynuclear aromatic hydrocarbon, we prefer itto be one containing not more than two aromatic nuclei since then theproducts are less likely to contain cross-linking.

Where these polymers are formed by our specified two component process,e.g. using a disulphonyl halide compound of the structure X.SO₂--Ar--SO₂.X and a second compound having the structure H--Ar'--H (whereAr' has the same possibilities as Ar), they will have repeating units ofthe structure --Ar--SO₂ --Ar'--SO₂ -- but where they are formed from ourmodified process using one or more compounds each having a singlearomatically bound sulphonyl halide group and an aromatically boundhydrogen atom, they will comprise randomly distributed units of thestructure --Ar--SO₂ -- where Ar may vary from unit to unit in the chain.

It will be appreciated that in the first mentioned process two or moredisulphonyl halide compounds of the general structure X.SO₂ --Ar--SO₂.Xmay be reacted with one or more aromatic compounds of the generalstructure H--Ar'--H.

As a further feature of our invention we provide polymers havingrepeating units of the structure --Ar--SO₂ -- as hereinbefore definedand units of the structure --Ar--CO-- where Ar has the possibilitieslisted above.

Polymers containing units of the structure --Ar--CO--, even when Arcomprises two benzene nuclei linked by a bridging group, tend to becrystalline in character.

Because of their ready preparation and good physical properties, ourpreferred polymers are those in which the residues Ar are derived frombenzene, diphenyl, compounds having the structure ##SPC9##

or derivatives of such residues wherein one or more of the aromaticallybound hydrogen atoms are substituted by other monovalent atoms orgroups. Of these polymers, we further prefer those in which at leastsome of the residues Ar are residues derived from compounds of thestructure IV or are derivatives of such residues wherein one or more ofthe aromatically bound hydrogen atoms are substituted by othermonovalent atoms or groups as these polymers are particularly suitablefor moulding to give strong, transparent products of high softeningpoint.

We prefer that where substituted derivatives of the residues are presentin the polymer chain, the substituents are halogen atoms or lowerhydrocarbon, ether or thioether groups or halogenated derivatives ofthese groups as the polymeric products are then inert to a wide varietyof chemicals. We particularly prefer the substituents, if any, to behalogen atoms, alkyl groups containing from 1 to 4 carbon atoms oralkoxy groups containing from 1 to 4 carbon atoms. We further preferthose polymers in which the aromatically bound hydrogen atoms aresubstituted, if at all, only on the carbon atoms meta to the --SO₂ --linkages because of their ease of preparation. On the whole, we preferthose polymers in which none of the aromatically bound hydrogen atomshave been replaced by other atoms or groups because of their remarkableinertness to acid or alkaline chemicals even at very high temperatures.

Those polymers having aromatic residues of the structure IV in which Pis oxygen, sulphur, a diol residue containing up to 4 carbon atoms, or adivalent aliphatic hydrocarbon radical containing from 1 to 4 carbonatoms in the chain between the aromatic nuclei and not more than 10carbon atoms altogether are formed from readily available monomers.Derivatives of such monomers where one or more of the aromatically-boundhydrogen atoms ortho to the bridging group P have been substituted byhalogen atoms or alkyl or alkoxy groups containing from 1 to 4 carbonatoms are also readily available.

Our preferred polymers which are generally thermally stable at very hightemperatures, even above their melting points consist of repeating unitshaving the structure ##SPC10##

where P is an oxygen atom or a sulphur atom, and R₁, R₂, R₃ and R₄ areeach selected from the group consisting of hydrogen atoms, halogenatoms, alkyl groups containing from 1 to 4 carbon atoms and alkoxygroups containing 1 to 4 carbon atoms.

Particular examples of such polymers are those formed from a combinationof units having the structure ##SPC11##

and units having the structure ##SPC12##

In general, we have found that increase of the number of units havingthe structure VI increases the softening point of our preferredcopolymers but also endows them with an increasingly brittle nature.Those of our preferred polymers in which these units comprise more than80% of the total number of units tend to be crystalline, insoluble andfabricated only with difficulty by standard plastic shaping processes.On the other hand, polymers containing below 5% of such units tend tohave low softening points. Therefore, we prefer those of our preferredpolymers in which the said units comprise from 5 to 80% of the totalnumber of units.

Those containing about 30% of such units have a very suitablecombination of softening point and tensile properties.

Our specified polymers have remarkably high softening points, frequentlyof the order of 300°C. or higher, are thermoplastic and, after treatmentto prevent them setting-up are stable for long periods in the melt. Theamorphous polymers are particularly suitable for fabrication at theirsoftening point without degradation to give shaped products which aregenerally strong, transparent and inert to a wide variety of chemicals,both acid and alkaline, even at temperatures near their softening point.They may be melt spun to yield fibres and filaments which may be used inapplications where resistance to chemical and high temperatures isdesired, for example in the manufacture of protective clothing, and theymay be extruded to give strong, transparent films which can withstandflexing and are suitable for wrapping or in electrical applicationswhere their high softening points are particularly advantageous. Theymay be shaped by any suitable process to give hard, strong, transparentmouldings having good stability to thermal degradation at temperaturesas high as 300°C. The shaped products may be used, for example, aselectrical insulants, for instance in transformer parts, switch gear andcondensers.

Many of the products are soluble in polar organic solvents such asnitrobenzene and dimethyl formamide. Fibres and films may be formed fromthe solutions and coatings deposited from the solutions, e.g. on wire,give good electrical insulation. The coated products may be used inconditions where elevated temperatures are encountered, for instance inelectrical transformers and high voltage switch gear. Those of ourproducts with molecular weights equivalent to reduced viscosities(measured on a solution of 1 gm. of the polymer in 100 ccs. of dimethylformamide at 25°C.) of 0.6 or more have a combination of physicalproperties such as tensile strength, modulus and softening point thatmakes them particularly suitable as moulding materials. We preferpolymers that are to be used in applications which make use of theirstrength to have reduced viscosities of at least 1.0.

The polymers show good adhesion to surfaces such as glass and metals andadhere particularly well to glass. Thus, they may be used as hightemperature thermoplastic adhesives for joining metal (e.g. stainlesssteel) parts, for example, in the manufacture of household goods such asovens, irons and the like.

The polymers may be mixed with other suitable ingredients such as dyes,pigments, heat and light stabilisers, plasticisers, mould-releaseagents, lubricants and fillers and may be blended with other polymericmaterials if desired.

The invention is illustrated by the following Examples in which allparts are expressed as parts by weight.

EXAMPLE 1

734.84 parts (2 moles) of diphenyl ether-4,4'-disulphonylchloride werefused with 308.52 parts (2 moles) of diphenyl at 90°C. under a slowstream of nitrogen in a heated vessel and after stirring for 30 minutes,4 parts of freshly sublimed ferric chloride were added to the melt. Thecatalyst dissolved rapidly on stirring with vigorous evolution ofhydrogen chloride. The reaction temperature was raised rapidly but themixture solidified at a bath temperature of about 180°C. The reactiontemperature was raised further to 280°C. at which temperature themixture was still solid. The total reaction time was 40 minutes.

The mixture was allowed to cool and the product was then broken up andstirred with 7850 parts of boiling isopropanol. The insoluble productwas filtered off and the process was repeated twice. On drying, theyield was 880 parts of a polymer having a reduced viscosity measured asa 1% solution in dimethyl formamide at 25°C. of 0.15. The polymer wasshown to be amorphous by X-ray examination and could be solvent castfrom dimethyl formamide to give transparent films.

EXAMPLE 2

550.64 parts (1.5 moles) of diphenyl ether-4,4'-disulphonyl chloride,137.76 parts (0.5 mole) of benzene-1,3-disulphonyl chloride and 307.56parts (2 moles) of diphenyl were fused together at 90°C. under a slowstream of nitrogen in a heated vessel. After stirring for 30 minutes,6.5 parts of ferric chloride were added and vigorous evolution ofhydrogen chloride began. The reaction temperature was raised until aftera further 20 minutes it reached 280°C. It was then raised slowly to300°C. and held there for 40 minutes. The total reaction time was 95minutes.

The product was treated as for Example 1 to give 870 parts of a clear,tough polymer having a reduced viscosity of 0.30. The polymer was shownto be amorphous by X-ray examination and could be solvent cast to givestrong films.

EXAMPLE 3

551.94 parts (1.5 moles) of diphenyl ether-4,4'-disulphonyl chloride,137.64 parts (0.5 mole) of benzene-1,3-disulphonyl chloride and 308.27parts (2 moles) of diphenyl were dissolved in 5650 parts of drynitro-methane at 95°C. under a slow stream of nitrogen and the mixturewas stirred. After 10 minutes, 15 parts of ferric chloride were addedand slow evolution of hydrogen chloride began. The stirred mixture washeated under reflux for 6 hours during which time the polymer wasprecipitated from solution as a fine powder.

The powder was filtered off and treated as in Example 1 to give 260parts of a polymer having a reduced viscosity of 0.041.

EXAMPLE 4

729.10 parts (about 2 moles) of diphenyl ether-4,4'-disulphonyl chlorideand 315.8 parts (about 2 moles) of diphenyl were dissolved in 7567 partsof cyclic tetramethylene sulphone at 105°C. and the mixture was stirredunder a slow stream of nitrogen. After 10 minutes stirring 8 parts offerric chloride were added as a solution in 630 parts of cyclictetramethylene sulphone. Slow evolution of hydrogen chloride began andthe reaction temperature was raised slowly to 210°C. over a period of 4hours and held there for a further 3 hours. The mixture was then cooledand poured into excess stirred iso-propanol and the insoluble productwas filtered off and treated as in Example 1 to give 520 parts of apolymer having a reduced viscosity of 0.07.

The results of this Example and Example 3 indicate that only lowmolecular weight products may be obtained from polymerisation insolution.

EXAMPLE 5

367.24 parts (1 mole) of diphenyl ether-4,4'-disulphonyl chloride,275.17 parts (1 mole) of benzene-1,3-disulphonyl chloride and 308.40parts (2 moles) of diphenyl were fused and stirred at 100°C. under aslow stream of nitrogen. After 10 minutes 2 parts of ferric chloridewere added. There was brisk evolution of hydrogen chloride. Over aperiod of 1 hour, the temperature of the reaction was raised to 320°C.at which temperature the product was a very viscous liquid. The mixturewas held for a further 45 minutes at 320°C. under a vacuum of 0.7 mm. ofHg. and then cooled.

The product was ground to a fine powder, dissolved in a hot mixture of9530 parts of dimethyl formamide and 195.2 parts of acetyl acetone andfiltered into a stirred excess of ethanol to precipitate the polymer.The product was 520 parts of a polymer which was found to be insolublein cold solvents. The rather low yield in this and following Examples 6to 12 is due to a certain amount of cross-linking occurring at the hightemperatures of the polymerisation, yielding some insoluble polymerwhich was removed during the filtration step.

EXAMPLE 6

735.12 parts (2 moles) of diphenyl ether-4,4'-disulphonyl chloride,154.20 parts (1 mole) of diphenyl and 170.20 parts (1 mole) of diphenylether were fused at 120°C. under a slow stream of nitrogen. 2 parts offerric chloride were added and the mixture stirred to dissolve thecatalyst. There was vigorous evolution of hydrogen chloride. Thepolymerisation and treatment of the polymer were as for Example 5 andthe yield was 620 parts of a polymer insoluble in cold solvents.

EXAMPLE 7

769.16 parts (2 moles) of diphenyl ether-4,4'-disulphonyl chloride and356.72 parts (2 moles) of diphenyl ether were fused and stirred at100°C. under a slow stream of nitrogen. After 10 minutes, 1.7 parts offerric chloride were added and there was brisk evolution of hydrogenchloride. The polymerisation and treatment of the polymer was as forExample 5 and the yield was 820 parts of a polymer having a reducedviscosity of 0.61 and a softening point of about 320°C.

EXAMPLE 8

The process of Example 7 was repeated and the product was ground to afine powder, dissolved in a hot mixture of dimethyl formamide and acetylacetone and filtered into a stirred excess of acetone to precipitate thepolymer. A polymeric product was obtained having a reduced viscosity of0.76 and a softening point of about 320°C.

EXAMPLE 9

735 parts (2 moles) of diphenyl ether-4,4'-disulphonyl chloride and 340parts (2 moles) of diphenyl ether were fused together at 110°C. andstirred for 10 minutes under a slow stream of nitrogen. 3.3 parts offerric acetoacetonate were then added to the mixture and the temperatureof the whole was raised slowly over a period of 4 hours 15 minutes to290°C. The mixture was then subjected to a vacuum of 0.3 mm. of Hg. andthe temperature raised slowly to 320°C. over a period of 25 minutes andheld there for a further 20 minutes. The melt was then cooled and theresultant solid ground to a powder and stirred and refluxed with 7850parts of isopropyl alcohol and 488 parts of acetyl acetone. The polymerwas then filtered off, washed and dried to yield 580 parts of a polymerhaving a reduced viscosity of 0.28. The polymer was soluble innitrobenzene and dimethyl formamide and could be solvent cast to givetransparent films.

EXAMPLE 10

The process of Example 9 was repeated using 10 parts of antimonypentachloride as catalyst. The temperature of the polymerisation waseventually raised to 340°C. over a period of 3 hours 10 minutes and theproduct was a polymer having a reduced viscosity of 0.21.

EXAMPLE 11

The process of Example 10 was repeated except that the fusiontemperature of the mixture when the catalyst was added was 130°C. and 48parts of antimony pentachloride were used. The polymerisationtemperature was maintained at 130°C. for a further 34 minutes and thenraised slowly to 310°C. over a period of 2 hours. The melt was thensubjected to a vacuum of 0.3 mm. of Hg. for 10 minutes at 310°C. beforebeing cooled.

The solid product was ground to a powder and dissolved in 9530 partsdimethyl formamide and the solution was filtered into an excess ofmethanol in order to precipitate the polymer. The precipitate was washedand dried at 80°C. for 3 hours under vacuum to yield 520 parts of apolymer having a reduced viscosity of 0.32.

EXAMPLE 12

367.24 parts (1 mole) of diphenyl ether-4,4'-disulphonyl chloride and402.42 parts (1 mole) of 4,4'-diphenoxy diphenylsulphone were fusedtogether at 140°C. and stirred under a slow stream of nitrogen for 10minutes when 8 parts of ferric chloride were added as catalyst. Thetemperature was raised to 310°C. for 2 hours after which a sample(Sample I) was removed from the melt. The remaining mixture wassubjected to a vacuum of 0.3 mm. Hg. for a further 45 minutes at 310°C.before cooling to give Sample II.

Both the samples were worked up as described in Example 11 and Sample Igave a polymer with a reduced viscosity of 0.37 while that of Sample IIwas 0.47.

EXAMPLE 13

619.30 parts (2 moles) of chlorobenzene-2,4-disulphonyl chloride, 185.44parts (1.2 moles) of diphenyl and 139.40 parts (0.8 mole) of diphenylether were fused at 140°C. and stirred under a slow stream of nitrogenfor 10 minutes before adding 4.1 parts of ferric chloride as catalyst asa 4.1% solution in tetrahydrofuran. The polymerisation temperature wasraised slowly to 190°C. over a period of 2 hours 15 minutes and to230°C. 20 minutes later when the product was still molten. The melt wascooled and the product ground to a powder, suspended in a mixture ofisopropyl alcohol and acetyl acetone, reprecipitated and dried to give ablack polymer.

EXAMPLE 14

2.7 parts of dry diphenyl ether-4-sulphonyl chloride (melting point44°C.) were fused in a closed vessel containing a nitrogen inlet andoutlet under an atmosphere of dry nitrogen and 0.09 part of dry ferricchloride was dissolved in the molten monomer. Moisture was rigorouslyexcluded from the reaction vessel. Evolution of hydrogen chloride gascommenced almost at once. After 7 minutes, the temperature was raised to180°C. and by that time 72% of the theoretical total amount of hydrogencloride had been evolved. The reaction mixture, which had formed a veryviscous foam, part solid, was cooled to a solid and powdered under anatmosphere of dry nitrogen and then the polymerization was recommencedby heating the powder to 110°C. The temperature was raised to 180°C.over a further 10 minutes when it was again reduced and the productagain powdered. The reaction was continued by heating the powderinitially to 150°C. under high vacuum and thereafter to 240°C. over aperiod of 15 minutes. The mass was held at this temperature for 20minutes before being cooled, dissolved in 30 parts of dimethyl formamideand filtered. The polymer was precipitated by pouring the solution intoa stirred mixture of 240 parts of acetone containing 30 parts ofconcentration hydrochloric acid. The precipitated polymer was filtered,washed with methanol and dried overnight at 60°C. under vacuum to give1.8 parts of poly(p-sulphonyl diphenyl ether) having a reducedviscosity, measured as a 1% solution in dimethyl formamide at 25°C. of1.2.

Samples of this polymer were compression moulded at 310°C. and 20 tonsper square inch pressure to form tough, transparent films of goodquality which could be creased repeatedly without fracture.

The dynamic mechanical moduli of the polymer were measured at varioustemperatures by the cantilever vibration method at 100 cycles. Themodulus dropped only slightly from 3.8 × 10¹⁰ dynes/cm² at -150°C. to1.9 × 10¹⁰ at +220°C.

EXAMPLE 15

2.8 parts of diphenyl ether-4-sulphonyl chloride were fused at 80°C.under dry nitrogen and 0.085 part of ferric chloride was then added.Moisture was rigorously excluded from the reaction vessel. After 10minutes the temperature was raised to 200°C. when 68% of the theoreticalamount of hydrogen chloride gas had been evolved. The mixture, which wasin the form of a viscid foam, was cooled to a solid and powdered underdry nitrogen and polymerisation was recommenced by heating the powder to100°C. under an absolute pressure of 0.1 mm. of mercury. The temperaturewas raised rapidly to 220°C. and held there for 2 hours then increasedagain to 240°C. for a further 90 minutes after which the mass wascooled, dissolved in 30 parts of hot dimethyl formamide and filtered andthe polymer was precipitated by pouring the solution into stirredchloroform. The precipitate was filtered, washed with methanol and driedfor 1 hour at 200°C. under high vacuum to give 1.8 parts of a polymerhaving a reduced viscosity of 1.35, measured as a 1% solution indimethyl formamide at 25°C.

Clear, transparent films were cast from a 10% solution of the polymer innitrobenzene and were found to be tough down to -60°C.

EXAMPLE 16

3.5 parts of diphenyl ether-4-sulphonyl chloride were fused at 80°C.under dry nitrogen and 0.09 part of ferric chloride was added to themelt. Moisture was rigorously excluded from the reaction vessel. After10 minutes, the temperature had been raised to 180°C. and the reactionwas 78% complete, calculated on hydrogen chloride evolution. The viscidfoamed mass was cooled to a solid, powdered and reheated to 150°C. underhigh vacuum. The temperature was increased to 240°C. over a period often minutes and held at a temperature of 240°-250°C. for a further 30minutes before cooling the mass. The cold polymer was dissolved in 40parts of dimethyl formamide, precipitated by pouring the solution into300 parts of well stirred 5N hydrochloric acid, filtered, washed withmethanol and dried overnight at 60°C. under vacuum to give 2.8 parts ofa polymer having a reduced viscosity of 0.99 as measured as a 1%solution in dimethyl formamide at 25°C.

The melt viscosity of the polymer was measured as 2.3 × 10⁵ poises at aconstant shear stress of 8.2 × 10⁵ dynes/sq. cm. at 350°C.

EXAMPLE 17

Using the process of Example 3, 2.9 parts of diphenyl ether-4-sulphonylchloride were polymerised using 0.07 part of ferric chloride ascatalyst. The temperature was raised to 170°C. over 9 minutes when thepolymerisation was calculated to be 67% complete by the measurement ofhydrogen chloride evolution. The resultant highly viscous mass wascooled to a solid, powdered and reheated to 150°C. After 12 minutes atthis temperature, the mass was cooled and powdered again and reheatedslowly to 250°C. under high vacuum over a period of 30 minutes. The masswas held at 250°C. for a further 10 minutes, cooled and worked up by themethod described in Example 3, to give 2.3 parts of a polymer having areduced viscosity of 0.78 measured as a 1% solution in dimethylformamide at 25°C.

EXAMPLE 18

33.3 parts of diphenyl ether-4-sulphonyl chloride were mixed with 0.8part of freshly sublimed ferric chloride and heated to 200°C. over 15minutes and then held at 200°C. for 2 hours with a slow stream of drynitrogen passing over the reaction mixture. During this time 96% of thetheoretical amount of hydrogen chloride was evolved. The product, whichwas a brown foamed mass, was powdered and then heated at 230° - 234°C.under an absolute pressure of 0.9 mm. of mercury for 5 hours. Theresulting brown polymer was dissolved in 300 parts of dry dimethylformamide and 1 part of aniline and shaken for 15 minutes. Four parts of8-hydroxy quinoline-5-sulphonic acid were added and shaking continuedfor a further 30 minutes. The solution was then passed down a 101/2 inchlong, 11/2 inch diameter column packed with Spence 100 - 200 mesh type Halumina. The intense dark green iron complex was absorbed on the first 2inches of the column. After the solution had been passed through thecolumn, any adsorbed polymer was washed through with a further 150 partsof dimethyl formamide. The polymer was precipitated from the almostcolourless solution by addition to 2500 parts of well stirred 5% aqueoushydrochloric acid. The white precipitate was filtered off, washed twicewith 500 parts of distilled water and once with 250 parts of methanoland finally dried at 120° in vacuum for 16 hours to give 25.6 parts ofpolymer. Analysis showed that the polysulphone contained less than 20parts per million of iron. The polymer could be held at 320°C. forseveral minutes without any detectable increase in viscosity and clear,very pale yellow films were moulded from the product at 320°C.

EXAMPLE 19

35 parts of diphenyl ether-4-sulphonyl chloride were polymerised by theprocess described in Example 18 using 1.62 parts of ferric chloride ascatalyst. The crude product was dissolved in 300 parts of dimethylformamide at room temperature and the solution was dissolved into fourequal parts each of which was shaken with one part of aniline for 15minutes. To each of three of the four parts was added the chelatingagent disclosed in the table below and the four parts were each filteredthrough the alumina column described in Example 18 and the polymer wasprecipitated from each and worked up by the process described in Example18. The results are set out below.

    ______________________________________                                                                Amount                                                                        used     Concentration                                                        (parts by                                                                              of iron in                                   Solution                                                                             Additional Chelating Agent                                                                     weight)  polymer (ppm)                                ______________________________________                                        A      None             --       70                                           B      8-hydroxyquinoline-5-                                                                          2.8      20                                                  sulfonic acid                                                          C      dimethyl glyoxime                                                                              0.7      30                                           D      ethylene diamine 1.8      30                                                  tetraacetic acid                                                       ______________________________________                                    

In each case the polymer obtained had a reduced viscosity of 0.72. Allfour samples could be held in the melt for long periods (up to 20minutes or more) without any detectable increase in viscosity.

EXAMPLE 20

7.73 parts of diphenyl ether-4-sulphonyl chloride and 13.09 parts ofdiphenyl-4-sulphonyl chloride were fused together at 130°C. undernitrogen. 0.39 part of ferric chloride was added to the melt and thetemperature slowly raised to 180°C. over a period of 26 minutes duringwhich period 80% of the theoretical amount of hydrogen chloride wasevolved. The foamed mass was cooled and powdered and the powder wasre-heated to 140°C. under vacuum, and then heated further to 210°C. overa period of 25 minutes. The mass was cooled and powdered again andheated once more to 120°C. under vacuum. The temperature was raised to240°C. over a period of 12 minutes and held at 240° - 250°C. for 130minutes. The mass was then cooled, dissolved in 220 parts of dimethylformamide to which was added 2.0 parts of aniline and 1.8 parts of8-hydroxyquinoline-5-sulphonic acid. The mixture was shaken for 20minutes and then passed through the alumina column described in Example18. The polymer was precipitated by pouring the solution obtained intodilute hydrochloric acid and was washed twice with hot methanol anddried for 18 hours at 100°C. under vacuum to yield 16.7 parts of acopolymer having a reduced viscosity of 0.91 and a very high softeningpoint, higher than 300°C. and containing only 20 parts per million ofiron.

An almost clear, colourless transparent film was cast from a solution ofthis polymer in nitrobenzene at 90°C.

EXAMPLE 21

A series of polysulphones were prepared following the process describedin Example 20 but using varying amounts of diphenyl ether-4-sulphonylchloride and diphenyl-4-sulphonyl chloride. Some properties of theproducts are set out below.

    __________________________________________________________________________    % diphenyl ether                                                              sulphone groups Modulus.sup.(2)                                               in copolymer    dynes/sq.cm.  Softening                                       (by I.R. analysis)                                                                       Form.sup.(1)                                                                       -150°C                                                                        +200°C.                                                                       point                                           __________________________________________________________________________    100        a.  s.                                                                             3.8 × 10.sup.10                                                                1.9 × 10.sup.10                                                                about 240°C.                             84         a.  s.                                                                             2.6 × 10.sup.10                                                                1.6 × 10.sup.10                                                                > 250°C.                                 74         a.  s.                                                                             3.9 × 10.sup.10                                                                2.0 × 10.sup.10                                                                > 250°C.                                 43         a.  s.                                                                             2.1 × 10.sup.10                                                                1.3 × 10.sup.10                                                                > 250°C.                                 23         a.  s.                                                                             not    measured                                                                             > 250°C.                                   O*       c.  i.                                                                             1.4 × 10.sup.10                                                                1.2 × 10.sup.10                                                                > 250°C.                                 __________________________________________________________________________    .sup.(1) a = amorphous                                                                   c = crystalline                                                     s = soluble                                                                             i = insoluble                                                      .sup.(2) Measured by the cantilever vibration method described by              Robinson in J. Sci. Instruments 32, page 2, 1955                              *This polymer did not foam during the polymerization process.            

All the amorphous copolymers could be solvent cast to give strong filmsbut the films became more and more brittle with decrease in the amountof diphenyl ether sulphone radicals in the polymer.

EXAMPLE 22

295 parts of diphenyl sulphide-4-sulphonyl chloride (melting point73.5°C.) were fused at 120°C. under dry nitrogen and 5.4 parts offreshly sublimed ferric chloride were added to the melt. The temperaturewas raised to 180°C. over a period of 12 minutes at the end of whichtime the amount of hydrogen chloride evolved was found to be 74% oftheoretical. The product was cooled, powdered and heated under highvacuum at a temperature rising from 140° to 230°C. over a period of 14minutes. The reaction mixture was finally held at 230° - 240°C. for 105minutes, thereafter cooled and dissolved in about 5000 parts of dimethylformamide. 51 parts of aniline were added to the solution followed by 35parts of 8-hydroxyquinoline-5-sulphonic acid. The mixture was shaken andthen filtered through the alumina-packed column described in Example 18.The polymer was precipitated into dilute hydrochloric acid, washed withhot methanol and dried at 100°C. under vacuum to yield 210 parts of apolymer having a reduced viscosity (measured on a solution of 1 gm. ofthe polymer in 100 ccs. of dimethyl formamide at 50°C.) of 0.56. X-rayexamination showed the polymer to be amorphous.

EXAMPLE 23

In each of a series of experiments 267 parts of diphenylether-4-sulphonyl chloride were heated with a catalyst (identifiedbelow) at 150°C. for 40 minutes to yield a foamed mass which was cooled,powdered and reheated under high vacuum (about 0.2 mm. Hg. absolutepressure) to a temperature of 230°C. over a period of 15 minutes. Thereaction mixture was finally held at 230°C. for 1 hour before it wascooled, dissolved in about 3000 parts of dimethyl formamide and treatedas described in Example 22 with 30.6 parts of aniline and 22 parts of8-hydroxyquinoline-5-sulphonic acid. In each case the polymer obtainedhad a reduced viscosity (measured on a solution of 1 gm. of polymer in100 ccs. of dimethyl formamide at 25°C.) in the range of 0.1 to 0.2.

    ______________________________________                                        Experiment  Catalyst        amount used                                       ______________________________________                                        A           Ferric orthophosphate                                                                         6.7 parts                                         B           Ferric fluoride 3.4 parts                                         C           Ferrous bromide 6.5 parts                                         D           Ferrous iodide  9.3 parts                                         ______________________________________                                    

EXAMPLE 24

15.1 parts of 4-phenoxybenzoyl chloride (boiling point 146°C. at 0.4 mm.Hg.) and 27.1 parts of diphenyl ether-4-sulphonyl chloride (meltingpoint 44°C.) were heated to 130°C. under a slow current of dry nitrogen.1.4 parts of freshly sublimed ferric chloride were dissolved in the meltand the temperature was raised to 220°C. over a period of 75 minuteswhen it was found that 79% of the theoretical amount of hydrogenchloride had been evolved. The mixture was cooled to yield a brittlefoam which was powdered and reheated to 230° to 240°C. for 40 minutesunder high vacuum. The mixture was then cooled again, ground to apowder, washed with cold dimethyl formamide followed by methanol anddried at 80°C. for 2 hours under vacuum to yield 29 parts of acrystalline polymer.

Infra-red analysis (by comparison with standard mixtures of homopolymersderived from each of the polymerisable monomers) showed the product tocontain 35% by weight of units having the structure ##SPC13##

Analysis of the sulphur content of the polymer showed it to contain 36%by weight of these units.

EXAMPLE 25

41.7 parts of 4-phenoxybenzoyl chloride and 5.3 parts of diphenylether-4-sulphonyl chloride were melted together at 170°C. and 2.5 partsof freshly sublimed ferric chloride were dissolved in the melt. After23/4 hours at 170°C, 86% of the theoretical amount of hydrogen chloridehad been evolved and the mixture was cooled, powdered and reheated to240°C. for 90 minutes under high vacuum (0.1 mm. Hg, abolute pressure).The product was cooled, ground to a powder, washed with hot acetone anddried overnight at 90°C. under vacuum to yield 36 parts of a polymerpartially soluble in nitrobenzene and soluble in 4,4'-diphenoxydiphenylsulphone at 200°C.

Infra-red analysis by the method described in Example 24 showed thepolymer to contain 90% by weight of units having the structure ##SPC14##

The polymer was highly crystalline, the crystal form being that of thehomopolymer derived from 4-phenoxybenzoyl chloride.

EXAMPLE 26

A series of polymerisations were effected following the process ofExample 25 but using varying concentrations of monomers and catalyst.The concentrations of each monomer and the catalyst and the form of theproducts obtained are set out below.

    Monomers*          Weight % of                                                                   units from I                                                                             Form of                                         Experiment                                                                            I      II     Catalyst                                                                             in polymer                                                                             polymer                                 ______________________________________                                        A       37.0   10.7   2.2    78       Crystalline                             B       32.4   16.1   2.4    67       Crystalline                             C       23.2   26.7   1.8    46       Crystalline                             ______________________________________                                         *I = 4-phenoxybenzoyl chloride                                                 II = diphenyl ether-4-sulphonyl chloride                                

I claim:
 1. A condenser comprising an electrically conductive portionwhich is electrically insulated by a shaped polysulphone formed ofrepeating units having the structure

    --Ar -- SO.sub.2 --

where Ar is a divalent aromatic residue derived from diphenyl or acompound having the structure ##SPC15## where X is --O-- or --S--, andAr may vary from unit to unit in the polymer chain.
 2. A condenseraccording to claim 1, in which the polysulphone is formed of repeatingunits having the structure ##SPC16##
 3. A condenser according to claim 1in which the polysulphone is formed of repeating units having thestructure ##SPC17##and units having the structure ##SPC18##
 4. Anelectrical structure comprising an electrically conductive componentelectrically insulated by a layer of a polysulphone formed of repeatingunits having the structure

    --AR -- SO.sub.2 --

where Ar is a divalent aromatic residue derived from diphenyl or acompound having the structure ##SPC19## whre X is --O-- or --S--, and Armay vary from unit to unit in the polymer chain.
 5. The structure ofclaim 4, in which the polysulphone is formed of repeating units havingthe structure ##SPC20##
 6. The structure of claim 5 in which thepolysulphone is formed of repeating units having the structure##SPC21##and units having the structure ##SPC22##
 7. A condensercomprising an electrically conductive portion which is electricallyinsulated by a shaped polysulphone formed of repeating units having thestructure

    --Ar -- SO.sub.2 --

where Ar is a divalent aromatic residue derived from benzene, apolynuclear hydrocarbon, diphenyl, a compound having the structure##SPC23## where P is --O--, --S--, --SO--, a divalent hydrocarbonradical, a residue of a diol containing only carbon atoms or groups ofthe structure --C--O--C--, and --C--S--C, in the chain between thehydroxyl groups, or substituted derivatives of any such aromaticresidues wherein one or more of the hydrogen atoms bound to aromaticrings are substituted by other monovalent atoms or groups, and Ar mayvary from unit to unit in the polymer chain.